Torque is often wrongly thought of as a measure of engine performance at low rpm. Big V-twins have ‘lots of low-down torque’, and inline four sportsbikes ‘lots of top-end power’, as if the two are discrete and opposite. They are different, but not opposites...

Ever wondered why your rear tyre wears down in the middle but not at the sides? It’s safer that way...

At first glance there’s nothing in common between touring on a Triumph Tiger 800 XC and a 250bhp MotoGP prototype. But there is.

I recently had a 3000-mile ride on a Tiger. Its Bridgestone Battlewings were 4000 miles-old at the start and, as you’d expect, the rear squared-off as the ride went on. 7000 miles isn’t a bad total, and the bike maintained its steering and stability. But eventually it shimmied a bit over white-lines as it rolled across its squared-off centre. And with plenty of tread left on the edges, it seemed a waste of rubber to chuck it away.

So why don’t manufacturers make rear tyres harder in the middle where they wear the most?...

Selecting a power mode on your bike? The future’s already been mapped out. Literally.

Fitting a litre sportsbike with a castrating low power engine mode sounds like a bad idea, even if you call it ‘Rain’ mode. And few electronic aids are as contentious because engine modes are, technically, voluntary restrictions. Each is, broadly speaking, an overlay of instructions directing the ECU to manipulate and reduce engine performance.

If ever a company has been through rough times, then surely Moto Guzzi has to be a contender for the role of ultimate survivor. In spite of so many obstacles over the years it is still churning out bikes and is today’s oldest brand of European motorcycle manufacturer with continuous production. A legacy of bad management, circumstance and I have no doubt also bad luck, has seen it diminish in size from its heyday down to a true minority player. In 2004 it was taken over...

Frames have got uglier and cheaper, but they’re straighter than ever. Suspension, on the other hand...

Last week’s Techwatch talked about how current production engines have close tolerances and matched components, and how automated mass-production reduces variability. If a modern engine makes 100bhp today, in 12 months’ time it’s likely the same model will also make 100bhp (although early BMW S1000RRs were an exception – bikes varied by up to 15bhp, and no-one knows why....

It’s long been a biking myth that in Japanese engine assembly plants, female workers are preferred to males for some jobs on the production line because they have smaller hands and greater dexterity. Having spent time at Suzuki’s vast Takatsuka Engine Plant in Hamamatsu, I can safely put that one to rest; it’s not true. They have plenty of both on the production lines.

Ducati’s Panigale 1199 has a single-sided swingarm. The new 899 has a double sided swingarm. Now that’s a good idea...

It’s intuitive to grip a wheel at the end of each axle to give yourself maximum control of stability and alignment (or, if we’re talking about front wheels, steering). It’s certainly easier – it’s more effort to play wheelbarrows if you only using one arm to hold the barrow wheel. But it also looks cool if you wave with your free hand.

In the list of pointless engine gimmicks, you’d surely put variable valve timing at number one. Only three production bikes have automatic VVT: Honda’s VFR800 VTEC (crude, two-stage system), Kawasaki’s 1400GTR (more sophisticated but barely noticeable) and, between 1991 and 1998, Suzuki’s Japan-only R-version 250 and 400 Bandits (crude and unnoticeable). And all of them gimmicks.

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Recent Articles

We're familiar with solid-state electronics in biking. Ignition swapped points for transistors in the 1970s, then went digital in the 1990s. Now, the need for greater power, fuel efficiency and emissions control means modern engines only work with computer-controlled fuelling, ignition, combustion and exhaust. When we open the throttle we pull the strings, but the ECU calls the shots. To do it, the ECU needs an accurate view of the world. And it gets it through its sensors.

A gyroscope is a rigid circular or spherical mass rotating around an axis and for over 100 years motorcycles have come with three of them: a front wheel, a rear wheel and a crank (if you're being pedantic you could include cams, balancer shafts, gearbox, clutch etc).
The classic mechanical model of a gyroscope ranges from the very small – electrons spinning around an atom's nucleus – to the very large – the Earth.

Most of us have an innate feel for balancing a high centre of gravity on a relatively short wheelbase. Say, like a motorbike. Its centre of gravity is the point at which the sum of the surrounding mass is zero, and is largely determined by the location of the engine, the heaviest part of the package. Usually the CoG is midway between the wheels (half the wheelbase) and 60 to 75cm off the ground; just above the engine, in front of your knees.
Or at least it is until you get on.

Anyone with fingers knows bikes vibrate, sometimes strongly enough to make picking your nose impossible. But how we perceive vibration depends on its type, pattern, frequency and cause.
Bikes are subject to different types of vibration. A bumpy road creates random forced vibration at medium to high frequency (around 5-35 Hz depending on vehicle speed). It's perceived as unpleasant, as is head buffeting caused by wind turbulence. Engineers and aerodynamicists try to minimise these bad vibrations.
But we usually talk about engine vibration. There are many sources...

From the launch of Yamaha's new Super Ténéré: "The exhaust pipe connection between the two headers is discontinued to give more character to the engine. The link pipe gives a flat feeling to the curve, so removing it makes the engine a bit more peaky."
This is all about exhaust gas. When a four-stroke is tuned for power it means more revs, and so the cylinders have thousandths of second to fill with fresh mixture, compress it, burn it and pump it out again. To get enough mixture in and out, inlet valves open early and exhaust valves stay open for longer – so both are open at the same time.

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